Method in which a mobile station receives information on a peripheral legacy base station in a legacy support mode

ABSTRACT

The present invention relates to a broadband wireless access system, and more particularly, to a method and an apparatus for acquiring system information in a mobile communication system in which a legacy system and an advanced system coexist. A method of receiving system information on a peripheral base station in a mobile communication system includes receiving a second message containing time information for receiving, through a second region of a serving base station, a first message broadcasted through a first region of the serving base station and receiving the first message through the first region of the serving base station using the time information, the first message containing system information on neighbor legacy base stations and/or on the first region of neighbor advanced base stations which operate in a mixed mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2010/004579, filed on Jul. 14, 2010,which claims the benefit of earlier filing date and right of priority toKorean Application No. 10-2010-0067812, filed on Jul. 14, 2010, and alsoclaims the benefit of U.S. Provisional Application Ser. No. 61/225,551,filed on Jul. 14, 2009, the contents of which are all incorporated byreference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a broadband wireless access system andmore particularly to a method for an advanced mobile station toefficiently acquire neighbor legacy BS information in a mobilecommunication system in which a legacy system and an advanced system arepresent together.

BACKGROUND ART

Handover (HO) is a procedure in which a mobile station (MS) moves froman air interface of one base station to an air interface of another basestation. A handover procedure of a general IEEE 802.16e system isdescribed below.

In an IEEE 802.16e network, a serving base station (SBS) may broadcastneighbor base station information through a neighbor advertisement(MOB_NBR-ADV) message in order to inform a mobile station (MS) of basicnetwork configuration information (topology).

The MOB_NBR-ADV message includes system information of a serving basestation and neighbor base stations, for example, preamble indexes,frequencies, handover (HO) optimization possibility, downlink channeldescriptor (DCD)/uplink channel descriptor (UCD) information, etc.

The DCD/UCD information includes information required for an MS toperform information exchange in downlink and uplink. For example, theDCD/UCD information includes HO trigger information, a medium accesscontrol (MAC) version of a base station, Media Independent Handover(MIH) capability information, etc.

A general MOB_NBR-ADV message includes only information associated withneighbor base stations of an IEEE 802.16e type. Information associatedwith base stations of the type other than an IEEE 802.16e type may bebroadcast to MSs through a service identity information advertisement(SII-ADV) message. Accordingly, an MS may acquire information associatedwith base stations of a heterogeneous network by requesting an SBS totransmit the SII-ADV message.

A procedure for performing handover by an MS, which has acquiredinformation associated with neighbor base stations using theabove-described method, in an IEEE 802.16e network is described below inmore detail.

The general handover procedure in an IEEE 802.16e network may include HOinitiation and preparation, HO execution, and HO completion.

An example of a basic handover procedure configured as described aboveis described below with reference to FIG. 1.

FIG. 1 illustrates an example of a handover procedure which may beperformed in an IEEE 802.16e system.

As shown in FIG. 1, first, a mobile station (MS) may access a servingbase station (SBS) to perform data exchange (S101).

The SBS may periodically broadcast information associated with neighborbase stations (BSs) located within the coverage of the SBS to the MSthrough an MOB_NBR-ADV message (S102).

The MS may begin to scan candidate HO BSs using an HO trigger conditionwhile communicating with the SBS. The MS may transmit a handover request(MOB_MSHO-REQ) message to request the SBS to perform a handoverprocedure when a handover condition is satisfied, for example, when apredetermined hysteresis margin value is exceeded (S103).

The SBS may inform candidate HO BSs included in the MOB_MSHO-REQ messageof the handover request received from the MS through an HO-REQ message(S104).

The candidate HO BSs may take precautions for the MS which has requestedhandover and transmit information associated with handover to the SBSthrough an HO-RSP message (S105).

The SBS may transmit the information associated with handover acquiredfrom the candidate HO BSs through the HO-RSP message to the MS through ahandover response (MOB_BSHO-RSP) message. The MOB_BSHO-RSP message mayinclude information required to perform handover such as an action timefor handover, a handover identifier (HO ID) and a dedicated HO CDMAranging code (S106).

The MS may determine one target BS among the candidate HO BSs based oninformation included in the MOB_BSHO-RSP message received from the SBS.Then, the MS may attempt to perform ranging by transmitting a CDMA codeto the determined target BS (S107).

The target BS which has received the CDMA code may transmit informationindicating whether or not ranging has succeeded and physical correctionvalues to the MS through a ranging response (RNG-RSP) message (S108).

Then, the MS may transmit a ranging request (RNG-REQ) message forauthentication to the target BS (S109).

The target BS which has received the ranging request message of the MSmay provide system information such as a connection identifier (CID)which can be used in the BS to the MS through a ranging response message(S110).

When the target BS has successfully completed authentication of the MSand has transmitted all update information, the target BS may notify theSBS of the MS of whether or not handover has succeeded through ahandover completion message (HO-CMPT) (S111).

Thereafter, the MS may exchange information with the target BS whichperforms handover (S112).

The above description has been given assuming that the handover processis performed between the MS and the BS which follow the IEEE 802.16estandard (WirelessMAN-OFDMA Reference System). Hereinafter, in thepresent specification, a system to which a general technology includingthe IEEE 802.16e standard is applied is referred to as a “legacy system”for ease of explanation. An MS to which the legacy technology is appliedis referred to as a “Yardstick MS (YMS)” or “legacy MS” and a BS towhich the legacy technology is applied is referred to as a “Yardstick BS(YBS)” or a legacy BS”.

A system to which an advanced technology including the IEEE 802.16mstandard (WirelessMAN-OFDMA Advanced System) is applied is referred toas an “advanced system”. An MS to which the advanced technology isapplied is referred to as an “advanced MS (AMS)”, and a BS to which theadvanced technology is applied is referred to as an “advanced BS (ABS)”.

The YBS has only a legacy zone (L zone or LZone) having a physicalchannel frame structure applied to a legacy system and the ABS maysupport only the AMS or both the AMS and the YMS. When the ABS supportsonly the AMS (WirelessMAN-OFDMA advanced system only), the ABS has onlyan advanced MS support zone (M zone or MZone) having a physical channelframe structure applied to an advanced system. When the ABS supportsboth the AMS and the YMS (WirelessMAN-OFDMA ReferenceSystem/WirelessMAN-OFDMA Advanced co-existing System legacy support),the ABS may operate in a mixed mode. In the following, the mixed modeoperation is described with reference to the case in which the legacysystem is an IEEE 802.16e system and the advanced system is an IEEE802.16m system. When the ABS operates in the mixed mode, the ABS hasboth the legacy zone (LZone) and the advanced MS support zone (MZone).In the mixed mode, the uplink (UL) zone may be divided into an L zoneand an M zone through Time Division Multiplexing (TDM) or FrequencyDivision Multiplexing (FDM).

The AMS may receive services from both the ABS and the YBS. That is, theAMS may receive a service through any one of the advanced MS supportzone and the legacy zone and may perform both a handover proceduredefined in the legacy system and a handover procedure defined in theadvanced system. The mixed mode operation is described below assumingthat the legacy system is an IEEE 802.16e system and the advanced systemis an IEEE 802.16m system as mentioned above.

While the AMS receives a service from an M zone of an ABS that supportsboth the AMS and the YMS, the AMS may need to be handed over to thelegacy system or to an L zone of another ABS. In this case, the AMS mayperform network reentry to a target BS (a YBS or an L zone of an ABSthat operates in the mixed mode) according to a network reentryprocedure defined in the legacy system. However, before performingnetwork reentry, the AMS may need to acquire information associated withneighbor legacy BSs or neighbor BSs that support the legacy system.

DISCLOSURE Technical Problem

An object of the present invention devised to solve problems of therelated art described above lies in providing a method for an advancedMS to efficiently acquire system information of a neighbor legacy BS.

Objects of the present invention are not limited to those describedabove and other objects will be clearly understood by those skilled inthe art from the following description.

Technical Solution

In accordance with one embodiment of the present invention to achievethe above objects, a method for a mobile station to receive neighborbase station information from a serving base station that operates in amixed mode in a mobile communication system in which a legacy system andan advanced system are present together may include receiving a secondmessage including time point information for receiving a first messagethrough a first zone of the serving base station through a second zoneof the serving base station, and receiving the first message through thefirst zone of the serving base station using the time point information.Here, the first message may include system information of at least oneof a neighbor base station of the serving base station, the neighborbase station supporting only the legacy system, and the first zone of aneighbor base station of the serving base station, the neighbor basestation operating in the mixed mode.

In accordance with another embodiment of the present invention toachieve the above objects, a mobile station for receiving neighbor basestation information from a serving base station that operates in a mixedmode in a mobile communication system in which a legacy system and anadvanced system are present together may include a processor, and aRadio Frequency (RF) module for transmitting and receiving a wirelesssignal to and from the base station under control of the processor.Here, when the processor has received, from a second zone of the servingbase station, a second message including time point informationindicating a time point for receiving a first message that is broadcastthrough a first zone of the serving base station, the processor mayperform a control operation for receiving the first message through thefirst zone of the serving base station using the time point information,and the first message may include system information of at least one ofa neighbor base station of the serving base station, the neighbor basestation supporting only the legacy system, and the first zone of aneighbor base station of the serving base station, the neighbor basestation operating in the mixed mode.

In the above embodiments, the time point information may include atleast one of offset information representing a time point at which thefirst message is broadcast from the first zone using an offset from atime point at which the second message is received, and intervalinformation indicating a period, at intervals of which the first messageis broadcast from the first zone.

Here, preferably, the offset information and the interval informationare determined on a frame by frame basis.

Preferably, the legacy system may be, but is not limited to, aWirelessMAN-OFDMA system and the advanced system is an IEEE 802.16msystem.

In addition, preferably, the first zone is an L zone (LZone) thatsupports the legacy system and the second zone is an M zone (Mzone) thatsupports the advanced system.

Further, preferably, the first message is a neighbor advertisement(MOB_NBR-ADV) message and the second message is an advanced neighboradvertisement (AAI_NBR-ADV) message.

Advantageous Effects

The mobile station may efficiently acquire neighbor legacy base stationinformation from an L zone of a base station by acquiring, through amessage broadcast from an M zone of the base station, informationrequired to receive a message including the neighbor legacy base stationinformation that is broadcast from the L zone of the base station.

Advantages of the present invention are not limited to those describedabove and other advantages will be clearly understood by those skilledin the art from the following description.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an example of a handover procedure which may beperformed in an IEEE 802.16e system.

FIG. 2 illustrates an example of a procedure for an AMS to acquireneighbor legacy BS information according to an embodiment of the presentinvention.

FIG. 3 illustrates an example of a procedure for an AMS to acquireneighbor legacy BS information according to another embodiment of thepresent invention.

FIG. 4 illustrates an example of a procedure for an AMS to acquireneighbor legacy BS information according to another embodiment of thepresent invention.

FIG. 5 is a block diagram illustrating exemplary structures of atransmitting end and a receiving end according to another embodiment ofthe present invention.

BEST MODE

The embodiments described below are provided by combining components andfeatures of the present invention in specific forms. The components orfeatures of the present invention can be considered optional unlessexplicitly stated otherwise. The components or features may beimplemented without being combined with other components or features.The embodiments of the present invention may also be provided bycombining some of the components and/or features. The order of theoperations described below in the embodiments of the present inventionmay be changed. Some components or features of one embodiment may beincluded in another embodiment or may be replaced with correspondingcomponents or features of another embodiment.

The embodiments of the present invention have been described focusingmainly on the data communication relationship between a terminal and aBase Station (BS). The BS is a terminal node in a network which performscommunication directly with the terminal. Specific operations which havebeen described as being performed by the BS may also be performed by anupper node as needed.

That is, it will be apparent to those skilled in the art that the BS orany other network node may perform various operations for communicationwith terminals in a network including a number of network nodesincluding BSs. The term “base station (BS)” may be replaced with anotherterm such as “fixed station”, “Node B”, “eNode B (eNB)”, “access point”,or “Advanced BS (ABS)”. In addition, the term “terminal” may also bereplaced with another term such as “User Equipment (UE)”, Mobile Station(MS)”, “Mobile Subscriber Station (MSS)”, “Advanced MS (AMS)”, or“Subscriber Station (SS)”.

The embodiments of the present invention may be implemented by variousmeans. For example, the embodiments of the present invention may beimplemented by hardware, firmware, software, or any combination thereof.

In the case in which the present invention is implemented by hardware,the methods according to the embodiments of the present invention may beimplemented by one or more application specific integrated circuits(ASICs), digital signal processors (DSPs), digital signal processingdevices (DSPDs), programmable logic devices (PLDs), field programmablegate arrays (FPGAs), processors, controllers, microcontrollers,microprocessors, or the like.

In the case in which the present invention is implemented by firmware orsoftware, the methods according to the embodiments of the presentinvention may be implemented in the form of modules, processes,functions, or the like which perform the features or operationsdescribed below. Software code can be stored in a memory unit so as tobe executed by a processor. The memory unit may be located inside oroutside the processor and can communicate data with the processorthrough a variety of known means.

The embodiments of the present invention can be supported by standarddocuments of at least one of the IEEE 802 system, the 3GPP system, the3GPP LTE system, and the 3GPP2 system which are wireless access systems.That is, steps or portions that are not described in the embodiments ofthe present invention for the sake of clearly describing the spirit ofthe present invention can be supported by the standard documents. Forall terms used in this disclosure, reference can be made to the standarddocuments. Especially, the embodiments of the present invention can besupported by one or more of P802.16-2004, P802.16e-2005, P802.16Rev2,and IEEE P802.16m which are standard documents of the IEEE 802.16system.

Specific terms used in the following description are provided for betterunderstanding of the present invention and can be replaced with otherterms without departing from the spirit of the present invention.

First Embodiment

In the following description, it is assumed that an AMS is receiving aservice from an M zone of an ABS that operates in a mixed mode and theAMS needs neighbor legacy BS information in order to perform, forexample, handover to a neighbor legacy BS.

System information of neighbor legacy BSs is included in a neighboradvertisement (MOB_NBR-ADV) message that is broadcast from an L zone ofthe ABS that operates in a mixed mode. However, to receive theMOB_NBR-ADV message broadcast from the L zone, the AMS first needs toacquire system information of the L zone (i.e., DCD/UCD information).That is, the MOB_NBR-ADV message includes both system information of theBS and system information of other neighbor BSs (i.e., deltainformation) and thus the AMS needs to acquire system information of theL zone in order to receive the MOB_NBR-ADV message.

If the AMS does not know when the MOB_NBR-ADV message of the L zone istransmitted, a significant delay time, which corresponds to aMOB_NBR-ADV message transmission period in the worst case, may occursince the MOB_NBR-ADV message of the L zone is broadcast at intervals ofa relatively long period even when the AMS has already acquired systeminformation of the L zone through a different method, for example,through a message directly received from the L zone or a messagetransmitted from the M zone.

Accordingly, an embodiment of the present invention suggests a methodfor notifying, in the M zone, an AMS of when the neighbor advertisementmessage is transmitted or of both when the neighbor advertisementmessage is transmitted and when system information of the L zone istransmitted.

Information indicating when the system information of the L zone istransmitted and when the neighbor advertisement message is transmittedmay be transmitted through a message that is transmitted to the AMS fromthe M zone. An example of this message includes an advanced neighboradvertisement (AAI_NBR-ADV) message of the M zone.

That is, the AAI_NBR-ADV message is generally used for an ABS totransmit neighbor BS information. This embodiment suggests thatinformation as to when the system information of the L zone istransmitted and information as to when the neighbor advertisementmessage of the L zone is transmitted be included in the AAI_NBR-ADVmessage.

In one method for an AMS to determine whether or not a legacy BS or anABS which operates in the mixed mode (i.e., an L zone of an ABS) ispresent around the AMS, the AMS may determine that a legacy BS or an Lzone of an ABS is present around the AMS if information as to when aneighbor advertisement message is transmitted is included in anAAI_NBR-ADV message. Alternatively, a field (for example, a greenzoneindicator) indicating whether or not a neighbor legacy BS is present maybe included in the AAI_NBR-ADV message and the AMS may determine whetheror not a neighbor legacy BS or an L zone of ABS is present through thefield.

Information as to when the neighbor advertisement message of the L zoneis transmitted, which will also be referred to as a reference pointerfor ease of explanation, may include offset information and intervalinformation.

The offset information indicates an offset from the time when a message(for example, an AAI_NBR-ADV message) including the reference pointer istransmitted to the time when the MOB_NBR-ADV message of the L zone istransmitted. Preferably, the offset information is set on a frame byframe basis.

The interval information indicates a period, at intervals of which theMOB_NBR-ADV message is transmitted from the L zone. Preferably, theinterval information is also set on a frame by frame basis.

Accordingly, once the AMS has acquired the offset information and theinterval information, the AMS can receive a MOB_NBR-ADV message of the Lzone at the time indicated by the offset information. The AMS can alsoreceive the MOB_NBR-ADV message in a next period indicated by theinterval information when the AMS has failed to receive the message atthe time indicated by the offset information.

The above procedure is described below in more detail with reference toFIG. 2.

FIG. 2 illustrates an example of a procedure for an AMS to acquireneighbor legacy BS information according to an embodiment of the presentinvention.

In the example of FIG. 2, it is assumed that a serving ABS operates inthe mixed mode and the AMS is receiving a service from an M zone of theserving ABS.

As shown in FIG. 2, first, the AMS may acquire information as to whensystem information (UCD/DCD information) of the L zone is transmittedand information as to when an MOB_NBR-ADV message is transmitted throughan AAI_NBR-ADV message received from the M zone of the serving ABS(S201).

Then, the AMS may receive a DCD/UCD of the L zone through the L zoneusing the time information acquired through the AAI_NBR-ADV message(S202, S203).

Then, the AMS may receive a MOB_NBR-ADV message through the L zone usingthe information as to the MOB_NBR-ADV message transmission time (S204).

Using the above method, the AMS can efficiently acquire systeminformation of the L zone of the ABS or neighbor legacy BSs without anunnecessary delay time.

According to another aspect of this embodiment, the information as towhen the DCD/UCD information of the L zone is transmitted may be omittedin the AAI_NBR-ADV message in the case where the AMS has alreadyacquired DCD/UCD information of the L zone.

According to another aspect of this embodiment, the AMS may acquireDCD/UCD information, which is included in a frame indicated by theinformation as to when the MOB_NBR-ADV message is transmitted, from theL zone.

Second Embodiment

According to another embodiment of the present invention, the AMS mayacquire UCD/DCD information of the L zone through the M zone. That is,the reference pointer information of the MOB_NBR-ADV message may stillbe included in the AAI_NBR-ADV message and DCD/UCD information, insteadof information as to when the DCD/UCD information is transmitted fromthe L zone, may be included in the AAI_NBR-ADV message. This method isdescribed below with reference to FIG. 3.

FIG. 3 illustrates an example of a procedure for an AMS to acquireneighbor legacy BS information according to another embodiment of thepresent invention.

In the example of FIG. 3, it is assumed that the serving ABS operates inthe mixed mode and the AMS is receiving a service from the M zone of theserving ABS.

As shown in FIG. 3, first, the AMS may acquire information as to whensystem information (full UCD/DCD information) of the L zone istransmitted and information as to when an MOB_NBR-ADV message istransmitted through an AAI_NBR-ADV message received from the M zone ofthe serving ABS (S301).

Since the AMS has already acquired the DCD/UCD information, the AMS mayreceive the MOB_NBR-ADV message through the L zone using the informationas to when the MOB_NBR-ADV message of the L zone is transmitted (S302).

Third Embodiment

According to another embodiment of the present invention, deltainformation among information included in the MOB_NBR-ADV message (i.e.,information different from the system information of the L zone fromamong the system information of neighbor BSs) and information as to whenDCD/UCD information is transmitted from the L zone may be included inthe AAI_NBR-ADV message. That is, this embodiment has the same effectsas when the AMS receives the MOB_NBR-ADV message through the M zone.This method is described below with reference to FIG. 4.

FIG. 4 illustrates an example of a procedure for an AMS to acquireneighbor legacy BS information according to another embodiment of thepresent invention.

In the example of FIG. 4, it is assumed that the serving ABS operates inthe mixed mode and the AMS is receiving a service from the M zone of theserving ABS.

As shown in FIG. 4, first, the AMS may acquire information as to whensystem information (UCD/DCD information) of the L zone is transmittedand delta information of an MOB_NBR-ADV message through an AAI_NBR-ADVmessage received from the M zone of the serving ABS (S401).

Since the AMS has already acquired the delta information, which can beacquired through the MOB_NBR-ADV message of the L zone, through theAAI_NBR-ADV message, the AMS may receive the DCD/UCD information fromthe L zone using the information as to when the system information(UCD/DCD information) of the L zone is transmitted (S402, S403).

Using the above method, the AMS can efficiently acquire systeminformation of neighbor legacy BSs.

According to another aspect of this embodiment, the information as towhen the DCD/UCD information of the L zone is transmitted may be omittedin the AAI_NBR-ADV message in the case where the AMS has alreadyacquired DCD/UCD information of the L zone.

In the above embodiments, the AMS may acquire information regardingneighbor legacy BS or information regarding the L zone of the ABS andmay perform scanning and/or handover to a neighbor legacy BS or to the Lzone of the ABS using the acquired information.

AMS and ABS Structure

An AMS and an ABS (FBS or MBS) according to another embodiment of thepresent invention in which the embodiments of the present invention canbe performed are described below.

The AMS may operate as a transmitter in uplink and may operate as areceiver in downlink. The ABS may operate as a receiver in uplink andmay operate as a transmitter in downlink. That is, each of the AMS andthe ABS may include a transmitter and a receiver for information or datatransmission.

The transmitter and the receiver may include a processor, a module, aportion, and/or a means for performing the embodiments of the presentinvention. Specifically, each of the transmitter and the receiver mayinclude a module (means) for encrypting a message, a module for parsingan encrypted message, an antenna for transmitting and receiving amessage, and the like. An example of such transmitting and receivingends is described below with reference to FIG. 5.

FIG. 5 is a block diagram illustrating exemplary structures of thetransmitting end and the receiving end according to another embodimentof the present invention.

A left part of FIG. 5 illustrates the structure of the transmitting endand a right part of FIG. 5 illustrates the structure of the receivingend. The transmitting and receiving ends may include antennas 5 and 10,processors 20 and 30, transmission modules (Tx modules) 40 and 50,reception modules (Rx modules) 60 and 70, and memories 80 and 90,respectively. Each pair of components may perform a correspondingfunction. The following is a detailed description of each of thecomponents.

The antennas 5 and 10 may function to transmit signals generated by thetransmission modules 40 and 50 to the outside and to receive wirelesssignals from the outside and deliver the wireless signals to thereception modules 60 and 70. Each of the transmitting and receiving endsmay include two or more antennas when a multiple antenna (MIMO) schemeis supported.

In each of the transmitting and receiving ends, the antenna, thetransmission module, and the reception module may constitute a RadioFrequency (RF) module.

The processors 20 and 30 generally control overall operations of the AMSand the ABS, respectively. Specifically, each of the processors 920 and930 may perform a control function for performing the embodiments of thepresent invention described above, a function to perform MAC framevariable control according to service characteristics and radioenvironments, a handover function, authentication and encryptionfunctions, and the like.

The processor of the AMS may control operations of the AMS forperforming a procedure for acquiring system information of the L zone ofthe ABS or a neighbor legacy BS using a method in which the AMS acquiresinformation required to receive an MOB_NBR-ADV message, which isbroadcast through an L zone of the ABS, through an M zone of the ABSthat operates in the mixed mode and receives an MOB_NBR-ADV message ofthe L zone using the acquired information.

The processor of the AMS may also perform overall control of theoperating procedures described in the above embodiments.

The transmission modules 40 and 50 may perform coding and modulation ofdata, which has been scheduled by the processors to be transmitted tothe outside, and then may deliver the resulting data to the antennas 5and 10, respectively.

The reception modules 60 and 70 may perform decoding and demodulationupon radio signals received from the outside through the antennas 5 and10 to restore the radio signals into original data and then may deliverthe original data to the processors 20 and 30, respectively.

The memories 80 and 90 may store programs for processing and control bythe processors and may also temporarily store input/output data items.The memories 80 and 90 may include a storage medium of at least one of aflash memory type, a hard disk type, a multimedia card micro type, acard type (for example, SD or XD memory), Random Access Memory (RAM),Static Random Access Memory (SRAM), Read-Only Memory (ROM), ElectricallyErasable Programmable Read-Only Memory (EEPROM), Programmable Read-OnlyMemory (PROM), a magnetic memory, a magnetic disc, and an optical disc.

The ABS may perform, through at least one of the modules describedabove, a control function for performing the embodiments of the presentinvention described above, Orthogonal Frequency Division Multiple Access(OFDMA) packet scheduling, Time Division Duplex (TDD) packet scheduling,and channel multiplexing functions, a function to perform MAC framevariable control according to service characteristics and radioenvironments, a high-speed traffic real-time control function, ahandover function, authentication and encryption functions, a functionto perform modulation/demodulation for data transmission, a high-speedpacket channel coding function, a real-time modem control function, andthe like or may further include means, modules, or portions forperforming these functions.

Those skilled in the art will appreciate that the present invention maybe embodied in other specific forms than those set forth herein withoutdeparting from the spirit and essential characteristics of the presentinvention. The above description is therefore to be construed in allaspects as illustrative and not restrictive. The scope of the inventionshould be determined by reasonable interpretation of the appended claimsand all changes coming within the equivalency range of the invention areintended to be embraced within the scope of the invention. In addition,claims which are not explicitly dependent on each other can be combinedto provide an embodiment or new claims can be added through amendmentafter this application is filed.

INDUSTRIAL APPLICABILITY

Although a method for acquiring legacy BS information and an MSstructure for the same in a broadband wireless access system have beendescribed with reference to an example in which the method and the MSstructure are applied to an IEEE 802.16m system, the method and the MSstructure may also be applied to various other mobile communicationsystems having femto BSs.

The invention claimed is:
 1. A method for a mobile station to receiveneighbor base station information from a serving base station in awireless access system, the method comprising: receiving a secondmessage including first time point information indicating a time pointat which a first message is broadcast from a first zone of the servingbase station through a second zone of the serving base station;receiving the first message from the first zone of the serving basestation using the first time point information, wherein the firstmessage including system information of at least a neighbor legacy basestation which supports only a legacy system or the first zone of aneighbor advanced base station which operates in a mixed mode; andperforming handover to one of the at least neighbor legacy base stationor the first zone of the neighbor advanced base station by using thesystem information included in the first message.
 2. The methodaccording to claim 1, wherein the first time point information includesat least: offset information representing a time point at which thefirst message is broadcast from the first zone using an offset from atime point at which the second message is received; or intervalinformation indicating a period, at intervals of which the first messageis broadcast from the first zone.
 3. The method according to claim 2,wherein the offset information and the interval information aredetermined on a frame unit basis.
 4. The method according to claim 3,further comprising receiving the system information of the first zone ina frame indicated by the first time point information.
 5. The methodaccording to claim 3, wherein: the first message further includes secondtime point information indicating a time point at which the systeminformation of the first zone is transmitted, and the method furthercomprises receiving the system information of the first zone using thesecond time point information.
 6. The method according to claim 1,wherein the first zone is an L zone (LZone) that supports the legacysystem and the second zone is an M zone (Mzone) that supports anadvanced system.
 7. The method according to claim 1, wherein the firstmessage is a neighbor advertisement (MOB_NBR-ADV) message and the secondmessage is an advanced neighbor advertisement (AAI_NBR-ADV) message. 8.A mobile station for receiving neighbor base station information from aserving base station in a mobile communication system, the mobilestation comprising: a processor; and a Radio Frequency (RF) module fortransmitting and receiving a wireless signal to and from the servingbase station under control of the processor, wherein, when a secondmessage, including time point information indicating a time point forreceiving a first message that is broadcast through a first zone of theserving base station, is received from a second zone of the serving basestation, the processor performs a control operation for receiving thefirst message through the first zone of the serving base station usingthe time point information, wherein the first message includes systeminformation of at least a neighbor legacy base station which supportsonly a legacy system or the first zone of a neighbor advanced basestation which operates in a mixed mode, and wherein the processorperforms handover to one of the at least neighbor legacy base station orthe first zone of the neighbor advanced base station by using the systeminformation included in the first message.
 9. The mobile stationaccording to claim 8, wherein the time point information includes atleast: offset information representing a time point at which the firstmessage is broadcast from the first zone using an offset from a timepoint at which the second message is received; or interval informationindicating a period, at intervals of which the first message isbroadcast from the first zone.
 10. The mobile station according to claim9, wherein the offset information and the interval information aredetermined on a frame unit basis.
 11. The mobile station according toclaim 10, wherein the processor performs a control operation forreceiving the system information of the first zone in a frame indicatedby the time point information.
 12. The mobile station according to claim10, wherein: the first message further includes second time pointinformation indicating a time point at which the system information ofthe first zone is transmitted, and the processor performs a controloperation for receiving the system information of the first zone usingthe second time point information.
 13. The mobile station according toclaim 8, wherein the first zone is an L zone (LZone) that supports thelegacy system and the second zone is an M zone (Mzone) that supports anadvanced system.
 14. The mobile station according to claim 13, whereinthe first message is a neighbor advertisement (MOB_NBR-ADV) message andthe second message is an advanced neighbor advertisement (AAI_NBR-ADV)message.
 15. A method for a base station that operates in a mixed modeto transmit neighbor base station information in a wireless accesssystem, the method comprising: broadcasting a second message includingfirst time point information indicating a time point at which a firstmessage is broadcast from a first zone of the base station through asecond zone of the base station; and broadcasting the first message fromthe first zone of the base station according to the first time pointinformation, wherein the first message includes system information of atleast a neighbor legacy base station which supports only a legacy systemor the first zone of a neighbor advanced base station which operates inthe mixed mode.
 16. The method according to claim 15, wherein the firsttime point information includes at least: offset informationrepresenting a time point at which the first message is broadcast fromthe first zone using an offset from a time point at which the secondmessage is received; or interval information indicating a period, atintervals of which the first message is broadcast from the first zone.17. The method according to claim 16, wherein the offset information andthe interval information are determined on a frame unit basis.
 18. Themethod according to claim 17, further comprising broadcasting the systeminformation of the first zone in a frame indicated by the first timepoint information.
 19. The method according to claim 17, wherein: thefirst message further includes second time point information indicatinga time point at which the system information of the first zone isbroadcast, and the method further comprises broadcasting the systeminformation of the first zone according to the second time pointinformation.
 20. The method according to claim 15, wherein the firstmessage is a neighbor advertisement (MOB_NBR-ADV) message and the secondmessage is an advanced neighbor advertisement (AAI_NBR-ADV) message.